The invention relates to a conductive cutaneous sheet or coating for applying an electric current to a person's skin for therapeutic or beauty treatment, comprising a layer of a settable composition spread over an area of skin and having a substantial electrical conductivity during setting.
The invention also relates to an apparatus employing such a coating applied as a facial mask.
U.S. Pat. No. 4,317,457 discloses an electrically conductive casting defining a cutaneous electrode for applying electric current to parts of the human body for therapeutical or beauty purposes. The casting according to this reference comprises a powder, typically a dental quality powder, which is settable when mixed with an excess quantity of water containing a dissolved salt, typically calcium chloride. Metal contacts are embedded in the casting for applying electric current supplied by a generator. Normally a counterelectrode comprising another casting is employed. As the casting becomes practically nonconductive when it hardens, the current is applied before setting of the casting is completed.
In use it has been found that the preparation of the electrically conductive castings, applying them to the person's skin, and monitoring the application of electric current requires skilled and trained operators. Further, the person being treated must keep the part of his/her body immobile to which the casting is applied until the casting has attained sufficient mechanical strength.
Thus therapeutic and aesthetic treatments of the skin by means of electric currents must be performed in clinics or otherwise under the care of skilled practitioners.
It thus seemed desirable to develop cutaneous electrode which could be applied and used by the person to be treated in cases where treatment does not otherwise require the monitoring by a skilled practitioner.
According to the invention there is provided a conductive cutaneous coating for application to an area of a person's skin for use in applying electric currents for therapeutic or beauty treatment, said coating comprising a layer of a settable composition, spread over an area of skin and having substantial electrical conductivity during setting, the improvement wherein the composition is a gel polymerizable when brought into contact with air and comprises a terniary mixture of polyvinyl alcohol, ethanol and water, and a plastifier physiological acceptable for topical application.
The polymerization of the gel thus formed results in the formation of a flexible coating which is intimately applied to the skin and follows slight deformation thereof throughout polymerization. The coating has a conductivity of the same order of magnitude as cutaneous tissue until polymerization is completed, in conditions comparable to those of known electrically conductive castings. Upon completion of polymerization the coating is removed in one piece or large strips, without sticking to the skin.
Preferably, the composition comprises 15 to 30% polyvinyl alcohol having a degree of hydrolysis greater than 85%, 7 to 15 wt % ethanol, 1.5 to 3 wt % water-soluble lanolin, 0.7 to 1.5 wt % glycerol, and the remainder water.
The preferred composition comprises 20 wt % polyvinyl alcohol, 10 wt % ethanol, 2 wt % water-soluble lanoline, 1 wt % glycerol, the remainder being water.
Preferably, the amount of polyvinyl alcohol is adjusted together with the selection of the degree of condensation to obtain a gel viscosity between 2,000 and 3,000 Pa.s.
The preferred kind of polyvinyl alcohol has an ester index of about 70%, and a degree of condensation so that the viscosity of a 4 wt % aqueous solution is about 3 Pa.s at 20.degree. C.
Concurrently with a gel capable of forming a conductive coating which the user can apply to his/her skin, it has also appeared desirable that the current generator be portable to enable the user to perform the treatment by himself or herself at home in cases where the actual treatment does not require the presence of a practitioner.
According to another aspect of the invention it is preferably for the treatment of large cutaneous areas to employ cutaneous electrodes having electrical conductivity parallel to the skin which is substantially that of the subjacent skin tissue. When applying voltage between two spaced points of the coating, the voltage gradients in the portions of the coating and the subjacent skin are similar. The treatment can be carried out by connecting two spaced points of the coating to the terminals of an appropriate generator. Thereupon it is unnecessary to use counter-electrodes for the return current or to form a gap in the coating to define a pair of electrodes. This is all the more so as the presence of such a gap between two coating portions has the tendency to produce relative large voltage gradients in the area of the gap and localized currents in this gap.
Thus the invention also provides an apparatus for cutaneous therapeutic or beauty treatment by applying pulsed electric current to facial skin, a conductive coating adapted to be applied as a facial mask, a lead connecting the conductive coating to the terminals of a generator, the improvement wherein the conductive coating comprises a one-piece facial mask of a gel polymerizable in contact with air and comprising 15 to 30 wt % polyvinyl alcohol having a degree of hydrolysis greater than 85%, 5 to 15 wt % ethanol, 1.5 to 3% water-soluble lanolin, 0.7 to 1.5 wt % glycerol, the remainder being water, the lead having two conductors each connected to a conductive plate disposed at electrically insulated ends of an arcuate head clip, the conductive plates bearing against the mask through porous pads soaked with a saline solution at a location at the rear of the cheekbones at ear level.
The combinations of the features of the apparatus participate in facilitating the nonprofessional application of the electrical currents for treatment.
These and other features and advantages will become apparent from the description which follows, given by way of example, of a preferred embodiment of the invention.